I was in the bar yesterday when I suddenly realized I desperately needed to pass gas. The music was really, really loud, so I timed my farts with the beat.
After a couple of songs, I started to feel better. I finished my beer and noticed that everybody was staring at me.
Then I suddenly remembered that I was listening to my iPod.
[The punchline caught me by surprise and so I laughed heartily for a good few minutes :)]